EXOSPHERE

Exosphere

The exosphere is a thin, atmosphere-like volume surrounding a planetary body where molecules are gravitationally bound to that body, but where the density is too low for them to behave as a gas by colliding with each other. In the case of bodies with substantial atmospheres, such as the Earth's atmosphere, the exosphere is the uppermost layer, where the atmosphere thins out and merges with interplanetary space. It is located directly above the thermosphere.

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exosphere

Noun

  1. the uppermost layer of a planet's atmosphere
  2. an extremely thin atmosphere, as on Saturn's moon Dione


The above text is a snippet from Wiktionary: exosphere
and as such is available under the Creative Commons Attribution/Share-Alike License.

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